tree 89921ffbfcb772100d358c2b7bc570c9894c7f0d
parent 2179f402e062f40a357759ad28717a79df062697
author Sylvain Munaut <tnt@246tNt.com> 1321021525 +0100
committer Harald Welte <laforge@gnumonks.org> 1321136615 +0100

core/rbtree: optimize rb_erase()

See kernel commit 55a63998b8967615a15e2211ba0ff3a84a565824

----
Tfour 4 redundant if-conditions in function __rb_erase_color() in
lib/rbtree.c are removed.

In pseudo-source-code, the structure of the code is as follows:

if ((!A || B) && (!C || D)) {
        .
        .
        .
} else {
        if (!C || D) {//if this is true, it implies: (A == true) && (B == false)
                if (A) {//hence this always evaluates to 'true'...
                        .
                }
                .
                //at this point, C always becomes true, because of:
                __rb_rotate_right/left();
                //and:
                other = parent->rb_right/left;
        }
        .
        .
        if (C) {//...and this too !
                .
        }
}

Signed-off-by: Wolfram Strepp <wstrepp@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
----

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>